Salix interior
Salix glauca
sandbar willow
glaucous willow, gray willow, gray-leaf willow, grey-leaf willow
erect or decumbent;
branches brownish, yellow-brown, gray-brown, or red-brown, villous or pilose to glabrescent;
branchlets yellow-brown or red-brown, sparsely to densely villous or tomentose to glabrescent.
stipules absent or rudimentary on early ones, rudimentary or foliaceous on late ones;
petiole 1–5(–9) mm, glabrous or sparsely villous adaxially;
largest medial blade linear to lorate, 60–160 × 4–11 mm, (6.5–)11–19(–31) times as long as wide, base cuneate, margins flat, remotely spinulose-serrulate (teeth 2–5 per cm), apex acute or subacuminate, abaxial surface thinly glaucous, densely villous or long-silky to glabrescent, adaxial slightly glossy, pilose or densely villous to glabrescent;
proximal blade margins entire;
juvenile blade reddish or yellowish green, moderately densely to sparsely long-silky abaxially.
stipules (marcescent or not), foliaceous or rudimentary on early and late ones;
petiole (usually deeply to shallowly grooved adaxially), 1–27 mm, (much longer than subtended bud);
largest medial blade usually hypostomatous, sometimes hemiamphistomatous or amphistomatous, usually narrowly elliptic, elliptic, usually oblanceolate or obovate, sometimes narrowly oblong or obovate, 27–82 × 6–39 mm, 1.4–4.8 times as long as wide, base usually cuneate or convex, sometimes rounded, rarely subcordate, margins slightly revolute or flat, usually entire, apex acute, acuminate, convex, or rounded, abaxial surface densely villous or villous-silky, tomentose, short- or long-silky, or pilose, hairs usually wavy or straight, sometimes curved, adaxial usually slightly glossy, sometimes dull, moderately densely villous, pilose, or long-silky to glabrescent;
proximal blade margins entire or serrulate;
juvenile blade sparsely or densely villous, tomentose, or long-silky abaxially.
abaxial nectary 0.5–1.1 mm, adaxial nectary ovate, narrowly oblong, or flask-shaped, 0.6–1.4 mm, nectaries distinct;
filaments hairy;
anthers 0.4–0.9 mm.
abaxial nectary 0.1–1 mm, adaxial nectary narrowly oblong, oblong, square, ovate, or flask-shaped, 0.5–1.3 mm, nectaries distinct, or connate and cup-shaped;
filaments distinct or slightly or partly connate, glabrous, or hairy on proximal 1/2;
anthers 0.4–0.8 mm.
adaxial nectary narrowly oblong, 0.4–1.1 mm, shorter to longer than stipe;
stipe 0.4–0.8 mm;
ovary obclavate to pyriform, glabrous, glabrescent, or long-silky, beak abruptly tapering to styles;
ovules 16–36 per ovary;
styles 0–0.2 mm;
stigmas flat, abaxially non-papillate with pointed tip, or broadly cylindrical, 0.3–0.7 mm.
abaxial nectary absent, adaxial nectary usually narrowly oblong, oblong, or ovate, sometimes flask-shaped, 0.4–1.8 mm, shorter to longer than stipe;
stipe 0.3–2.8 mm;
ovary pyriform or obclavate, densely villous, tomentose, short-silky, or pubescent, beak usually gradually tapering to styles, sometimes gradually tapering to or slightly bulged below styles;
ovules 6–22 per ovary;
styles connate to distinct 1/2 their lengths or more, 0.3–1.6 mm;
stigmas flat, abaxially non-papillate with rounded tip, or slenderly or broadly cylindrical, 0.2–0.8 mm.
(4–)5–8(–10) mm.
4.5–9 mm.
(flowering throughout season); staminate 20–61 × 4–10 mm, flowering branchlet 3–20 mm; pistillate loosely flowered, slender or stout, 20–67 × 5–9 mm, flowering branchlet 3–19 mm;
floral bract (sometimes greenish), 1.5–3.5 mm, apex acute, acuminate, or rounded, entire, erose, or toothed, abaxially hairy either proximally or distally, hairs wavy.
staminate 14–53 × 5–17 mm, flowering branchlet 1–25 mm; pistillate densely to sometimes loosely flowered, slender, stout, subglobose, or globose, 15–83 × 7–21 mm, flowering branchlet 2–37 mm;
floral bract tawny, brown, bicolor, or greenish, 1–3.4 mm, apex convex or rounded, entire, abaxially hairy, hairs wavy, crinkled, or straight.
= 38.
= 76, 95, 114, 152.
Salix interior
Salix glauca
Sometimes Salix interior is treated as a subspecies of S. exigua (R. D. Dorn 1998). Salix exigua and S. interior hybridize and apparently intergrade in the western Great Plains; because the area of overlap is relatively small and distinctiveness of the two taxa is not compromised by hybridization and introgression, it is best to treat them as separate species.
Leaves on sylleptic shoots are usually very densely silky. Salix interior sometimes has shoots that arise from buds on either side of the normal axillary bud. They do not seem to be directly related to the stipules because they are enclosed by the petiole. Catkins with both staminate and pistillate flowers are rare in S. interior, but a Quebec specimen had some catkins predominantly pistillate and others staminate; most were a mixture. The flowers were not teratological, but a mature capsule contained aborted ovules.
Hybrids:
Salix interior forms natural hybrids with S. exigua var. exigua. Controlled pollinations using S. interior (as S. exigua) from southern Ontario (A. Mosseler 1990) successfully produced F1 hybrids with S. bebbiana, S. discolor, S. eriocephala, and S. petiolaris. Seed production was usually relatively low, except in crosses with S. discolor. In general, F1 viability was relatively low in crosses with these members of subg. Vetrix. No seeds were produced in crosses with members of subgenera Protitea or Salix. Morphology of the hybrids usually was intermediate between the two parents, but when S. petiolaris was used as the maternal parent, the F1s more closely resembled that species. J. Salick and E. Pfeffer (1999) extended these findings to show that, although crosses between S. interior (as S. exigua) and S. eriocephala are partially sterile, their clonal growth parameters (sprouting, shoot length, and biomass production) are strong and thus permit these partially sterile hybrids to exist as successful individuals and perhaps to “... make a contribution to interspecific gene flow over time.” Of particular taxonomic interest is that, in this cross, the staminate parent has a significant influence on leaf shape, whereas in the cross S. eriocephala × S. petiolaris it is the pistillate parent that is significant for leaf shape. Relatively few hybrids resembling those produced by Mosseler have been recognized in nature, but it is possible that the unusually broadly leaved plants named S. interior var. exterior and var. wheeleri, from northern Maine, Nebraska, New York, and West Virginia, and probably elsewhere, may be hybrids. Phenological isolation may be strong enough to prevent crosses in nature (A. Mosseler and C. S. Papadopol 1989) with the earlier flowering S. eriocephala and S. petiolaris, a barrier that even an occasional period of overlap cannot breach.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 5 (4 in the flora).
Occurrence of Salix glauca is disjunct in western Siberia; var. glauca is known from Scandinavia.
Salix glauca is ubiquitous, highly polymorphic, and polyploid. It appears to have four major variations that are treated in different ways. European floras have treated it as an undivided polymorphic species(A. K. Skvortsov 1999), as several distinct species (K. H. Rechinger 1964b), or as comprising several subspecies (Rechinger 1993; G. W. Argus et al. 1999; B. Jonsell and T. Karlsson 2000+, vol. 1). In North America, Argus (1965) treated the four central tendencies as widely intergrading “phases” of a single species, later adopting varietal rank, whereas E. Hultén (1968) recognized them as subspecies. In view of the fact that the four elements are confluent over wide areas, there may be some merit in recognizing them as informal phases, but varietal rank is used here.
All specimens from Iceland named Salix glauca are S. arctica and those from Svalbard, Norway, are S. lanata Linnaeus.
The major reason for the high variability within Salix glauca seems to be high, and probably recurrent, polyploidy. Tetraploids, pentaploids, hexaploids, and octoploids are known in the species, and two of the subspecies include three ploidal levels. There also are intergrading geographical variations that are the basis for the recognition of infraspecific taxa.
Hybrids:
Salix glauca forms natural hybrids with S. arctica, S. arctophila, S. ballii, S. barclayi, S. boothii, S. brachycarpa, S. eastwoodiae, S. myricoides, S. niphoclada, S. pedicellaris, and S. planifolia.
The following key will help identify the varieties, but there are extensive areas of overlap among them and many intermediates.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stipules often marcescent, foliaceous on late leaves, usually prominent, linear, narrowly elliptic, or lanceolate, 2-17 mm; branches red-brown or gray-brown or brownish; branchlets densely villous to glabrescent; proximal blades: margins entire; floral bracts 1.2-2.5 mm; staminate flowering branchlets 1-14 mm; ovaries obclavate or pyriform; Alaska, Canada | → 2 |
1. Stipules sometimes marcescent or rudimentary, if foliaceous, usually inconspicuous, oblong, elliptic, or ovate, 1-8(-10) mm; branches usually yellow-brown or red-brown; branchlets usually sparsely villous or tomentose; proximal blades: margins entire or serrulate; floral bracts 1-3.4 mm; staminate flowering branchlets 1.5-25 mm; ovaries pyriform; northern Canada east of Mackenzie River, Greenland, Rocky Mountains | → 3 |
2. Shrubs, 0.3-1 m; branchlets densely villous; petioles 1-9 mm; largest medial blades: apex acute, sometimes acuminate, or convex, adaxial surface moderately densely villous, or long-silky to glabrescent; staminate catkins 14-26 mm; filaments distinct or partly connate, glabrous or hairy on proximal 1/2; pistillate catkins stout to subglobose, flowering branchlets 2-19 mm; stipes 0.4-1.8 mm; Alaska, Northwest Territories, w Nunavut, n Yukon. | var. stipulata |
2. Shrubs, 0.3-6 m; branchlets soon becoming pilose or glabrescent; petioles 4-27 mm; largest medial blades: apex acuminate to convex, adaxial surface often sparsely long-silky or pilose; staminate catkins 19-45 mm; filaments distinct, glabrous; pistillate catkins slender to stout, flowering branchlets 3-37 mm; stipes 0.5-2.8 mm; c Alaska, British Columbia, Northwest Territories, Yukon. | var. acutifolia |
3. Stipules 0.9-2.8-8(-10) mm, sometimes marcescent; floral bracts usually brownish; largest medial blades: petiole 3-14 mm; Alberta, British Columbia, Rocky Mountains, Saskatchewan to New Mexico. | var. villosa |
3. Stipules 1-2.1-4 mm, usually deciduous (in autumn); floral bracts usually tawny; largest medial blades: petiole 2-9 mm; c, e Canada, Greenland, St. Pierre and Miquelon. | var. cordifolia |
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